Immobilization of Glucose Oxidase on Magnetic Nanoparticles Modified with Chitosan and Sodium Tripolyphosphate.

In the last decades, the utilization of chitin-containing wastes has become an urgent task. The current work is aimed at studies on the use of chitosan (one of the main chitin components) for the preparation of magnetically separable biocatalysts. A multicomponent biocatalyst based on glucose oxidase (GOx) immobilized on Fe3O4 nanoparticles modified with chitosan and sodium tripolyphosphate was synthesized. The carboxyl groups of GOx were pre-activated with 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). Fourier-transform infrared spectroscopy and low-temperature nitrogen physisorption proved successful modification of the magnetically separable support with a fine layer of chitosan. The presence of target functional groups on the support surface was also confirmed. The activity and stability of the biocatalyst were investigated in the oxidation reaction of D-glucose to D-glucono-d-lactone. The immobilized biocatalyst showed slightly lower activity than that for the native enzyme. However, the immobilized enzyme can be easily separated from the reaction mixture by an external magnet and reused practically without activity loss. The ratio of the biocatalyst components providing maximum activity and stability was determined. It has been shown that the immobilization of GOx by the method described above results in an expansion of the operating range of pH and temperatures by 15-20 % compared to the native enzyme. The synthesized biocatalyst can be used to produce gluconic acid and determine the concentration of D-glucose in various fluids.